Kiyomasa Nakagawa

Factors affecting the occurrence of bacteremia associated with tooth extraction

This study examined the factors that affect the occurrence of bacteremia associated with tooth extraction and the kinds of bacteria causing this bacteremia. Bacteremia was found in 132 (72.1%) of 183 patients who had one or more teeth extracted for various reasons. Bacteremia occurred more frequently when teeth were extracted because of inflammatory dental diseases. The occurrence of bacteremia also increased with the number of teeth extracted and the age of the patients. When the volume of blood lost during surgery was > 50 ml and the time required for the operation exceeded 100 min, the occurrence of bacteremia was also higher. Anaerobes were isolated from 104 (78.8%) of the 132 cases of bacteremia. Of the 187 isolates obtained, three (1.6%) were aerobes, 51 (27.3%) were facultative anaerobes (including microaerophils), and 133 (71.1%) were anaerobes. Among facultative anaerobes and microaerophils, the most frequently isolated bacterial genera were Lactobacillus (n = 15), Streptococcus (n = 13), and Staphylococcus (n = 12); and among anaerobes, Eubacterium (n = 40), Peptostreptococcus (n = 40), and Propionibacterium (n = 20).

A comparative CT evaluation of pharyngeal airway changes in class III patients receiving bimaxillary surgery or mandibular setback surgery

OBJECTIVE The purpose of this study was to compare the morphologic changes of the upper airway space in Class III patients who underwent mandibular setback or bimaxillary surgery (maxillary advancement and mandibular setback) by computed tomography at 2 levels: soft palate and base of tongue. METHODS The sample consisted of 47 subjects in 2 groups who had been diagnosed as having Class III skeletal deformities and had been treated by mandibular setback or bimaxillary surgery (maxillary advancement and mandibular setback). Anteroposterior, lateral, and cross-sectional area dimensions of the airway at the level of soft palate and base of tongue were measured pre- and postoperatively on computed tomography images. RESULTS Anteroposterior dimensions of the airway decreased in both groups (P < .0001); however, the reduction was significantly less in cases treated with bimaxillary surgery (P < .05). In the mandibular setback surgery group, the cross-sectional area of the airway decreased significantly (P < .001). Although the cross-sectional area of the airway decreased in the bimaxillary surgery group, the reduction was not statistically significant (P > .05). CONCLUSIONS This study suggests that bimaxillary surgery can prevent narrowing of the upper airway in the correction of Class III deformities in comparison with mandibular setback surgery used as the sole treatment. Computed tomography was valuable in determining the effects of surgical treatment on pharyngeal airway dimensions.

Immunohistochemical localization of a urokinase-type plasminogen activator system in squamous cell carcinoma of the oral cavity: association with mode of invasion and lymph node metastasis.

The binding of urokinase-type plasminogen activator (uPA) to its receptor (uPAR) has been implicated in cancer invasion and metastasis. This activity is known to be regulated by several inhibitors such as plasminogen activator inhibitors (PAIs). To elucidate the participation of the uPA system in the malignant behaviour of squamous cell carcinoma (SCC) in the oral cavity, uPA, uPAR, PAI-1 and -2 expression and localisation in 34 primary oral cancers were examined immunohistochemically. The results were then compared with clinicopathological findings. The positive rates of uPA, uPAR, PAI-1 and -2 expression were 23.5, 29.4, 29.4 and 11.8%, respectively. uPA expression correlated with mode of cancer invasion according to Yamamoto-Kohamas criteria (p < 0.01) and with secondary regional lymph node metastasis. uPAR expression also correlated with mode of invasion. In particular, the tumours of both uPA- and uPAR-positive [uPA(+)/uPAR(+)] cases were highly invasive. In the present study, neither PAI-1 nor PAI-2 expression correlated with clinicopathological parameters. However, PAI-2 negative cases of uPA(+)/uPAR(+) were significantly more invasive (p < 0.0001). Such uPA(+)/uPAR(+)/PAI-2(-) cases almost always showed secondary lymph node metastasis (p < 0.01). These results indicate that the uPA system plays a significant role in the invasive and metastatic processes of oral SCC, and that this system may be a powerful aid in evaluating the clinical course or prognosis of patients with oral cancer.

The use of polylactic acid/polyglycolic acid copolymer and gelatin sponge complex containing human recombinant bone morphogenetic protein-2 following condylectomy in rabbits.

PURPOSE To examine the results of a polylactic acid/polyglycolic acid copolymer and gelatin sponge complex (PGS) with or without recombinant human bone morphogenetic protein-2 (rhBMP-2) used to treat condylar defects in rabbits. MATERIAL AND METHODS Adult male Japanese white rabbits (n=60; 3kg; 12-16 weeks old) were divided into three groups of 20 each. All rabbits underwent condylectomy. In the two implanted groups, PGS with or without 5 microg of rhBMP-2 was implanted to the condylar defect without fixation. No material was implanted into the control group. Animals were sacrificed at 2, 4, 8, 12 and 24 weeks postoperatively, and the temporomandibular joints (TMJs) were examined histologically. RESULTS Four weeks after implantation, growth of bone and cartilage-like tissue was observed in all rabbits that received PGS implants (with and without rhBMP-2). A cartilage-like layer was derived from the bone marrow at the operated surface. There was no growth of bone tissue in the control rabbits, but they also had a cartilage-like layer directly derived from the operated surface. CONCLUSION This study demonstrated that PGS with or without rhBMP-2 could induce regeneration of new bone and cartilage-like tissue in the TMJ.

The effect of mandibular setback or two-jaws surgery on pharyngeal airway among different genders

Cephalometric studies show significant gender differences in the size of the pharyngeal airway space. This study aimed to investigate and compare morphologic changes after mandibular setback or two-jaws surgery on the pharyngeal airway in men and women using computed tomography (CT). The sample included 34 women and 13 men diagnosed with Class III skeletal deformities, who had been treated by mandibular setback or bimaxillary surgery (maxillary advancement and mandibular setback). Anteroposterior, lateral and cross-sectional area dimensions of the airway, at the level of soft palate and base of tongue, were measured pre- and postoperatively on CT images. In the mandibular setback group, the anteroposterior and cross-sectional area of the pharyngeal airway at the level of the soft palate and base of tongue were significantly reduced for men or women (P<.05). In the two-jaws surgery group, only midsagittal anteroposterior dimensions at the same levels were significantly decreased for men or women (P<.05). The difference between any values measured between men and women who received bilateral sagittal split ramus osteotomy setback surgery or two-jaws surgery for the treatment of class III anteroposterior discrepancy were not statistically significant (P>.05). This study suggests that oropharyngeal airway measurements, important for airway patency, do not demonstrate sex dimorphism.

Horizontal changes in the condylar head after sagittal split ramus osteotomy with bent plate fixation

OBJECTIVE The purpose of this study was to evaluate the horizontal changes in the condylar head with bent plate fixation after sagittal split ramus osteotomy (SSRO) with and without a Le Fort I osteotomy. STUDY DESIGN Of 47 Japanese patients with mandibular prognathism, 24 underwent SSRO and 23 underwent SSRO in combination with a Le Fort I osteotomy. A 3-5-mm gap was made between the proximal and distal segments, and a bent plate was fixed with 4 screws in each side of the mandible. The angle of the condylar long axis, as well as the anteroposterior and mediolateral displacement of the condylar head were assessed preoperatively and postoperatively by computerized tomography (CT). RESULTS There was no significant difference in reduction in mandibular length between SSRO alone and SSRO with Le Fort I on the axial view of a 3-dimensional CT. There were no significant differences between pre- and postoperative horizontal changes in the condylar long axis or in the anteroposterior and mediolateral displacement of the condylar head, although the length of the proximal segment in SSRO with Le Fort I osteotomy was significantly shorter than in SSRO alone (P < .05). CONCLUSION These results suggest that the use of a bent plate for SSRO does not change preoperative angle or position significantly in setback surgery, regardless of the addition of Le Fort I osteotomy.

Statin-induced bone morphogenetic protein (BMP) 2 expression during bone regeneration: an immunohistochemical study.

OBJECTIVES The purpose of this study was to investigate bone morphogenetic protein (BMP) 2 expression after implantation of a statin and recombinant human BMP-2 (rhBMP-2) and to compare the bone regeneration capability of these substances in the rabbit nasal bone using immunohistologic methods. STUDY DESIGN Twelve adult male Japanese white rabbits (n = 12; age 12-16 weeks, weight 2.5-3.0 kg) were divided into 3 experimental groups and 1 control group. A total of 48 bone defects, 4 per rabbit, were created in the nasal bone while preserving the nasal membrane. In the experimental groups, 1 group was implanted with 10 mg of a statin dissolved in 0.2 mL water with an atelocollagen sponge (ACS); the second group was implanted with 5 microg rhBMP-2 with an ACS; and in the third group only the ACS was implanted. No material was implanted in the control group. Animals were killed at 1, 2, and 4 weeks after surgery. The parts that had been operated on were removed and prepared for histologic assessment. The expression of BMP-2 was evaluated using immunohistochemistry, and double-immunostaining for BMP-2 and Ki-67 was observed by fluorescent microscopy. RESULTS No significant differences were observed between the statin/ACS group and rhBMP-2/ACS group at 1, 2, and 4 weeks after surgery. The number of cells which stained positively for BMP-2 increased significantly in both of the implanted groups compared with the control group (P < .0001). The positive fluorescent double-immunostaining for BMP-2 and Ki-67 was similar in both implanted groups. CONCLUSION This study suggests that statin/ACS implants show BMP-2 expression and osteoinductive activity that is similar to those of rhBMP-2/ACS implants.

The assessment of trigeminal sensory nerve paraesthesia after bilateral sagittal split osteotomy: modified somatosensory evoked potentials recording method

Trigeminal neurosensory impairment is frequently observed following orthognathic surgery. The purpose of the present study is to visualize the degree of trigeminal nerve impairment following bilateral sagittal split osteotomy (BSSO). Twenty patients who underwent BSSO were in the present study. To record the modified somatosensory evoked potentials (SEP), two electrostimulation clips were applied. One clip was placed on the mucous surface of the lower lip and the other was placed on the skin surface. Each contact surface contained a separate 2 mm diameter silver anode and cathode attached to a 5 x 15 mm basement plate. The results obtained using this method revealed that complete recovery from neural impairment was observed in 7 cases (36.8%) on the right operative side and 4 (20.0%) on the left side at 6 months postoperatively. A definite delay in latency was observed on the left operative side at all the examination periods. The recovery period evaluated by the SEP method was longer than that of the objective two-point discrimination thresholds. Clinical records obtained showed considerable implications for trigeminal nerve function after BSSO.

Detection of cfxA and cfxA2, the β-lactamase genes of Prevotella spp., in clinical samples from dentoalveolar infection by real-time PCR

ABSTRACT While most bacteria involved in dentoalveolar infection are highly susceptible to penicillin, some Prevotella strains exhibit resistance to this agent through the production of β-lactamase. The production of β-lactamase by Prevotella spp. is in turn associated with the expression of the genes cfxA and cfxA2. The aim of the present study was to determine the prevalence of cfxA and cfxA2 in Prevotella strains by use of real-time PCR and to assess the performance of this molecular method for the direct detection of the genes in 87 clinical samples (pus and root canal exudates) from dentoalveolar infection. Production of β-lactamase by each isolate was determined using a nitrocefin disk. β-Lactamase production was seen in 31% of Prevotella isolates, while all isolates of other species were β-lactamase negative. The penicillin resistance of isolates strongly correlated with the production of β-lactamase. Real-time PCR was found to detect the cfxA and cfxA2 genes from at least five cells per reaction mixture (5 × 103 CFU/ml of pus). Using real-time PCR, the presence of cfxA and cfxA2 was evident for all 48 β-lactamase-positive Prevotella strains. In contrast, neither β-lactamase-negative Prevotella (n = 91) or non-Prevotella (n = 31) strains were positive for the genes. In this study, 31 of the 87 samples yielded β-lactamase-positive Prevotella results, and cfxA and cfxA2 were detected in all 31 samples. Of the 56 culture-negative samples, 8 (14%) were positive for cfxA and cfxA2 by the real-time PCR. This sensitive and specific molecular method offers a rapid clinical test for aiding in the selection of an appropriate antibiotic for treatment of dentoalveolar infection. Although penicillin remains largely effective in the treatment of dentoalveolar infection, β-lactamase-stable antibiotics should be considered in cases in which β-lactamase-positive Prevotella strains are involved.

Skeletal stability after mandibular setback surgery: comparisons among unsintered hydroxyapatite/poly-L-lactic acid plate, poly-L-lactic acid plate, and titanium plate.

PURPOSE The purpose of this study is to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with an unsintered hydroxyapatite (u-HA)/poly-L-lactic acid (PLLA) plate, PLLA plate, or titanium plate. PATIENTS AND METHODS Of 60 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with a u-HA/PLLA plate system, 20 underwent SSRO with a PLLA plate system, and 20 underwent SSRO with a conventional titanium plate system. The time-course changes in condylar long-axis and skeletal stability were assessed by use of axial, frontal, and lateral cephalograms. RESULTS Compared with the u-HA/PLLA group, the titanium group showed a significantly greater change in the right condyle angle between initially and 1 month (P = .0105) and intercondylar axes angle between 1 and 3 months (P = .0013). The PLLA group showed a significantly greater change than the titanium group (P = .0043) and u-HA/PLLA group (P = .0002) in terms of ramus inclination between 1 and 3 months; however, there were no significant differences among the 3 groups in the other measurements for each time interval. CONCLUSION This study suggests that there are no significant differences in postoperative time-course changes among a u-HA/PLLA plate system, PLLA plate system, and conventional titanium plate system.